• Journal of Biosystems Engineering
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• v.37 no.1
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• pp.58-64
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• 2012

Purpose: The objective of this study was to investigate the feasibility of anaerobic digestion of Chinese cabbage waste juice (CCWJ) and swine manure(SM). Methods: The anaerobic digestion test was conducted under batch and continuous conditions at mesophilic temperature ($36-38^{\circ}C$). The batch test was divided into Experiment I and II. In the Experiment I, biogas potential and production rate of CCWJ was evaluated. In Experiment II the effect of F/M ratio (2.0, 3.2, 4.9) at mixture ratio of 25:75(CCWJ: SM, % vol. basis) on biogas yield was studied. Results: CCWJ produced biogas and methane yield of 929 and 700 mL/g VS added respectively. The biogas yield from the mixture of CCWJ and SM was almost same at F/M ratio of 2.0 and 3.2 but dropped by 14% when F/M ratio increased from 3.2 to 4.9. In continuous test the mixture of CCWJ and SM (25:75, % vol. basis) produced biogas yield of 352 mL/g VS added which is around 11% higher compared to biogas yield from SM alone. Addition to biogas yield digester performance was also improved with co-digestion of CCWJ with SM. Conclusions: The results showed that the anaerobic digestion of CCWJ with SM could be promising for improving both the biogas yield and digester performance at mesophilic temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.65-75
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• 1995

The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The results indicated that even the vety lean mixture, which is normally not flammable in single chamber type, could be burned within. a comparatively short time by using sub-chamber with stratified charge method. And the lean inflammability limit of mixture in a main chamber was about ($\phi_m$cr=O.46, when the equivalence ratio of a sub-chamber was $\phi_s$= 1.0. Initial time of pressure increase and total burning times were decreased and maximum combustion pressure. was increased as the equivalence ratio of both sub and main chamber approached unity. Specifically, initial time of pressure increase and total burning times were greatly affected rather by. the equivalence ratio of sub-chamber than that of main chamber. The maximum combustion pressure was little affected if the total equivalence ratio lies in the same range.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.83-89
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• 1999

The electrical properties due to mixture ratio of linear low density polyethylene(LLDPE) and ethylene vinyl acetate(EVA) films are studied. An experimental specimen is selected as LLDPE/EVA of thickness 200${\mu}{\textrm}{m}$ produced by mixture ratio of 50 : 50, 60 : 40, 70 : 30 and 80 : 2 wt%. In temperature range from $25^{\circ}C$ to 12$0^{\circ}C$, the measurement of volume resistivity using a highmegohm meter is performed within 10 minutes since each voltage of DC 100 V, 250 V, 500 V and 1000 V is applied, according to the step voltage method. From FT-IR spectrum for an analysis of physical properties, it can be confirmed that LLDPE blended with EVA shows an absence of carbonyl groups(1735 $cm^{-1}$, C=0) and ether groups(1242 $cm^{-1}$, C-O). The peak of LLDPE and EVA made of mixture ratio of 70 : 30 at 2$\theta$ =21.4$^{\circ}$ in the results of XRD is higher than the others. In the experiment for volume resistivity characteristics in order to investigate the electrical properties of specimen, it is confirmed that volume resistivity is decreased with the increase of the molecular motion and temperature.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.2
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• pp.51-60
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• 2003

An experimental research program is being undertaken to develop a regeneratively-cooled experimental thrust chamber of liquid rocket engine using liquefied natural gas and liquid oxygen as propellants. Prior to firing test using a regenerative cooling with liquefied natural gas in this program, several firing tests were conducted with water as a coolant. Experimental thrust chambers with a thrust of about 10tf were developed and their firing test facility was built up. Injector used in the thrust chamber was of shear-coaxial type appropriate for propellants of gas and liquid phase and cooling channels are of milled rectangular configuration. Periodical variation of the soot deposition and discoloration was observed through an eyes' inspection on the inner wall of a combustion chamber and a nozzle after each firing test, and an intuitive concept of the periodical variation of mixture ratio near the inner wall of a combustion chamber and a nozzle at once was brought about and analyzed quantitatively. Thermal heat flux to the coolant was calculated and modified with the periodical variation model of mixture ratio, and the increment of coolant temperature at cooling channels was compared with measured one.

• Fashion & Textile Research Journal
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• v.13 no.5
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• pp.790-796
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• 2011

This study was designed to investigate the influence of ratio of anionic/nonionic surfactant mixture on detergency of particulate soil under various solutions. The detergency of the particulate soil was determined by adhesion of particle to fabric and its removal from fabric separately. The PET fabric and ${\alpha}-Fe_2O_3$were used as materials of textile and model of particulate soil, respectively. The detergency was investigated as a function of surfactants concentration, ionic strength, kinds of electrolyte and mole numbers of oxyethylene ether of nonionic surfactant in different ratio of anionic/nonionic surfactant mixture. Although some deviations exist, the adhesion of particle to fabric generally increased with decreasing its removal from fabric. The detergency of particulate soil on PET fabric was relatively higher in anionic/nonionic surfactant mixed solution than in each single surfactant solution, but the influence of ratio of anionic/nonionic surfactant mixture on detergency of particulate soil was low. Generally the detergency of particulate soil on fabric was at its maximum at 0.1% surfactant concentration, $1{\times}10^{-3}$ ionic strength, $Na_5P_3O_{10}$ electrolytes and 10 mole numbers of oxyethylene ether of nonionic surfactant, regardless of ratio of anionic/nonionic surfactant mixture.

• Korean Journal of Medicinal Crop Science
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• v.21 no.3
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• pp.174-178
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• 2013

Lime-bordeaux mixture has been used to prevent diseases in the field of ginseng. The purpose of this study is to investigate the efficacy of lime-bordeaux depending on the concentration and treatment time on major diseases of ginseng such as Alternaria blight and anthracnose, and to evaluate the root growth of ginseng. Lime-bordeaux caused damage on leaf when it was sprayed on ginseng between April and early May. No difference was found in root growth by spraying lime-bordeaux mixture between ratio 4-4 and 8-8 ratio in concentration. Plot of 6-6 raito and 8-8 ratio appeared to be similar efficacy compared to that of practical chemical control. However, the plot of 4-4 ratio showed lower than that of chemical control.

• Applied Biological Chemistry
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• v.35 no.4
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• pp.286-293
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• 1992

This study was investigated on the change of physico-chemical properties at various mixture ratio of improved Meju and Natto during the aging of soybean paste. pH was increased on the improved Meju with increasing the mixture ratio of Natto, but pH was decreased in Korean traditional Meju. Change of nitrogen compound was 3 times higher and aging was faster in increased ratio of Korean traditional Meju than that of improved Meju. Brown color was not changed as compared to the initial stage, however the value of brown color was higher in the Korean traditional Meju than that of other group. In sensory evaluation, the mixture ratio of improved Meju, Korean traditional Meju and Natto (48 : 48 : 5) was the best acceptables.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.731-738
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• 2002

Recently, as large constructions on the coast are performed frequently, surface layer stabilization method which Is one of the improvement methods for dredged soft clay has been applied. However, there have been few studies about the surface layer stabilization method. The purpose of this study is to clarify characteristics of ultra-soft marine clay and hardening agent. Also, optimal mixture ratio of hardening agent was verified through the laboratory tests such as statistical analysis and pilot tests. Laboratory tests were performed with proper hardening agent and test soil and standard mixing tables of hardening agent were determined according to ground conditions through statistical analysis. Also, applicability of surface layer stabilization method to field was verified by pilot tests. From the results of the tests, it was found that hardening agent materials such as cement, slag, fly-ash, inorganic salts, arwin, gypsum etc. affect on the appearing compressive strength. It was defined optimal mixture ratio which satisfies the required compressive strength from the statistical analysis. Also, It was compared the effect of ground improvement by cements and hardening agents through the pilot tests. This study will serve as data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.211-212
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• 2012

ZnO submicron particles were grown on Au-catalyzed Si substrate by a vapor phase transport (VPT) growth process under different mixture gas ratio at growth temperature of $900^{\circ}C$. The structural and optical properties of the ZnO submicron particles were investigated by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL). The ZnO submicron particles could be clustered with the $O_2/Ar$ mixture gas ratio(%) higher than 10%, and it was mainly determined by the gas ambient. Particularly, when the $O_2/Ar$ mixture gas ratio was 30%, it was observed the ZnO submicron particles with diameters in the range of 125 to 500 nm and the narrowest full width at half maximum (FWHM) of XRD and PL spectra with $0.121^{\circ}$ and 92 meV, respectively. It was found that the structural and optical properties of the ZnO submicron particles were improved with increasing the $O_2/Ar$ mixture gas ratio through the XRD and PL spectra.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.101-107
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• 2022

This study proposes the deconvolution method for the nanoindentation test results of geopolymer employing the Gaussian mixture model. Geopolymer has been studied extensively as an alternative construction material because it emits relatively lower CO₂ compared to ordinary Portland cement. Geopolymer is made of aluminosilicate and alkaline solution, and the Si/Al molar ratio affects its mechanical properties. Previous studies revealed that the Si/Al molar ratio of 1.8~2.0 results in the highest compressive strength, and the Si/Al molar ratio over 1.8 degrades the compressive strength of geopolymer severely; however the reason for the compressive strength degradation is still unclear. To understand the effect of the Si/Al molar ratio on the geopolymer structure, this study exploits the nanoindentation. The phase deconvolution of the indent modulus data is successful using the Gaussian mixture model, and it is observed that the Si/Al molar ratio alters the homogeneity of the geopolymer. Geopolymer becomes more homogeneous up to an Si/Al molar ratio of 1.8 at which geopolymer exhibits the highest compressive strength. The examination of this study is assumed to be adopted as evidence of strength degradation by the Si/Al ratio higher than the optimum value.